KR20210014769A - Impact resistant coating compositions - Google Patents

Abstract

The present invention comprises (a) (i) a film-forming resin having two or more functional groups, and (ii) a binder having a curing agent reactive with the functional groups of the film-forming resin; And (b) relates to a curable coating composition comprising solid vulcanized rubber particles non-reactive with the binder. The curable coating composition is a solid particulate powder coating composition. The invention also relates to a multi-layer coating system and a method of making the curable coating composition.

Description

Impact resistant coating composition {IMPACT RESISTANT COATING COMPOSITIONS}

The present invention relates to an impact resistant coating composition, a method of making the coating composition, and a substrate at least partially coated with the composition.

Cold rolled steel found in metal substrates such as springs and coils is prone to chipping, scratching and other physical damage. To prevent or reduce such damage, an impact resistant coating is typically applied on the surface of the substrate or on a corrosion resistant primer previously applied to the substrate. However, by increasing the impact resistance of the coating, other desirable properties such as chemical resistance and Taber resistance are often adversely affected.

Significant efforts have been made in the development of topcoats that reduce or prevent chipping, scratching and other physical damage to metal substrates. While these coatings provide some degree of impact resistance and other desirable properties, they still exhibit some drawbacks. For example, some of the currently available impact resistant coatings exhibit an undesirable appearance, while other currently available coatings exhibit poor impact resistance and cushioning around the curvature of non-planar substrates such as metal springs and coils. .

In addition, some currently available impact resistant coatings exhibit poor impact resistance at low temperatures of about -40°C. For example, some currently available impact resistant coatings including core-shell structures, thermoplastic blends, fibrous materials and/or rubber adducts have been shown to exhibit poor impact resistance at low temperatures of about -40°C. Turned out.

Accordingly, it is desirable to provide an improved impact resistant coating that exhibits good impact resistance at low temperatures such as about -40°C.

The present invention provides a binder comprising (a) (i) a film-forming resin comprising two or more functional groups, and (ii) a curing agent reactive with the functional groups of (i); And (b) relates to a curable coating composition comprising solid vulcanized rubber particles non-reactive with the binder. In addition, the curable coating composition is a solid particulate powder coating composition.

The invention also relates to a method of making a curable coating composition. The method comprises a film-forming resin comprising two or more functional groups by mixing a combination of solid components; A curing agent reactive with the functional groups of the film-forming resin; And forming a mixture comprising solid vulcanized rubber particles that are non-reactive with the film-forming resin and a curing agent. Then the mixture is melted and further mixed. The molten mixture is cooled and ground to form a solid particulate curable powder coating composition.

The invention also provides a first coating layer; And a second coating layer deposited on the first coating layer. The first and/or second coating layer comprises: (a) (i) a film-forming resin comprising two or more functional groups, and (ii) a binder comprising a curing agent reactive with the functional groups of (i); And (b) solid vulcanized rubber particles that are non-reactive with the binder. Further, the curable coating composition forming the first and/or second coating layer is a solid particulate powder coating composition.

For the purpose of the following specific description, it should be understood that the present invention can conceive various alternative modifications and sequences of steps, except when otherwise specified. In addition, except in any embodiment or where otherwise indicated, all numerical values expressing amounts of ingredients used in the specification and claims, for example, are to be understood as being modified in all instances by the term “about”. Accordingly, unless otherwise indicated, the numerical parameters set forth in the following specification and in the appended claims are approximations that may vary depending on the desired properties to be obtained by the present invention. At the very least, also not wishing to limit the application of the equivalence theory to the claims, each numerical parameter should be inferred by applying conventional rounding techniques, at least in light of the number of significant numerical values reported.

Although numerical ranges and parameters describing the broad scope of the present invention are approximate values, numerical values described in specific examples are reported as precisely as possible. However, any numerical values inherently contain certain errors that inevitably arise from the standard deviations found in their individual test measurements.

Further, it is to be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is meant to include all subranges between the recited minimum value 1 and the recited maximum value 10 (including), that is, a minimum value of 1 or more and a maximum value of 10 or less. Is intended.

In this application, unless otherwise specified, the use of the singular includes the plural and the plural includes the singular. In addition, the use of “or” herein means “and/or” unless otherwise specified, but “and/or” may be explicitly used in certain cases. Also, herein, unless otherwise specified, the use of the singular expression means “one or more”. For example, the singular form of film-forming resin, curing agent, vulcanized rubber particles, etc. refers to one or more of any of these items.

As mentioned, the present invention relates to curable coating compositions. The terms “curable”, “cure” and the like as used herein in combination with a coating composition mean that at least some of the components constituting the coating composition are polymerizable and/or crosslinkable. The curable coating composition of the present invention may be cured at room temperature by heat or by other means such as actinic radiation. As used herein, “ambient conditions” refer to the conditions of the surrounding environment (eg, temperature, humidity, and substrate of an indoor or external environment in which the substrate is located). The term “actinic radiation” refers to electromagnetic radiation capable of initiating a chemical reaction. Actinic radiation includes, but is not limited to, visible light, ultraviolet (UV) light, X-ray and gamma radiation.

The curable coating composition of the present invention includes a binder. As used herein, “binder” refers to the primary constituent material that holds all components together upon curing of the curable coating composition applied to the substrate. The binder comprises one or more, such as two or more film-forming resins. As used herein, "film-forming resin" is a resin capable of forming a self-supporting continuous film on at least a transverse surface of a substrate upon removal or curing of any diluent or carrier present in the composition. Refers to. In addition, the term "resin" as used herein is used interchangeably with "polymer", and the term "polymer" refers to oligomers and homopolymers (eg, prepared from a single monomer species), copolymers (eg, two or more monomers). Prepared from species), terpolymers (eg, prepared from three or more monomeric species) and graft polymers.

The film-forming resin may include any of a variety of thermosetting film-forming resins known in the art. The term “thermosetting” as used herein refers to a resin in which the polymer chains of a polymeric component are linked together by covalent bonds, so that upon curing or crosslinking irreversibly “harden”. This property is generally related to the crosslinking reaction of the composition components, which is often induced, for example by heat or radiation. The curing or crosslinking reaction can also be carried out under ambient conditions. Once cured or crosslinked, the thermosetting resin will not melt upon application of heat and is insoluble in solvent.

In some examples, the film-forming resin comprises a thermoplastic resin. The term “thermoplastic,” as used herein, refers to a resin that includes polymeric components that are not linked by covalent bonds, and thus can undergo a liquid flow upon heating and are soluble in certain solvents.

Alternatively, the curable coating composition of the present invention is substantially free of, essentially free of, or completely free of thermoplastic resins. The term “substantially free of thermoplastic resin” means that the curable coating composition contains less than 1,000 ppm (parts per million by weight) of a thermoplastic resin, based on the total weight of the composition, and “essentially comprises a thermoplastic resin. "No" means that the curable coating composition contains less than 100 ppm of a thermoplastic resin based on the total weight of the composition, and "no thermoplastic resin" means that the curable coating composition contains 20 based on the total weight of the composition. Means containing less than ppb (parts per billion by weight) of thermoplastic resin (including the absence of thermoplastic resin).

Non-limiting examples of suitable film-forming resins include (meth)acrylate resins, polyurethanes, polyesters, polyamides, polyethers, polysiloxanes, epoxy resins, vinyl resins, copolymers thereof and combinations thereof. . As used herein, “(meth)acrylate” and like terms refer to both acrylates and the corresponding methacrylates. The film-forming resin is, but is not limited to, a carboxylic acid group, an amine group, an epoxide group, a hydroxyl group, a thiol group, a carbamate group, an amide group, a urea group, an isocyanate group (including a block isocyanate group) and their It can have any of a variety of reactive functional groups, including combinations.

As mentioned, resins used to form the binder include, but are not limited to, epoxy resins. The epoxy resin may contain two or more epoxide functional groups. The epoxide functional groups may be terminal and/or pendant on the polymer chain. As used herein, “pendant group” refers to a functional group attached to and extending from the backbone of a polymer. The epoxy resin may also contain any additional functional groups described above. For example, the epoxy resin can contain one or more hydroxyl groups. The hydroxyl group and any other additional functional groups may be terminal and/or pendant on the polymer chain. Non-limiting examples of epoxy resins include, but are not limited to, diglycidyl ether of bisphenol A, polyglycidyl ether of polyhydric alcohol, polyglycidyl ester of polycarboxylic acid, and combinations thereof. Non-limiting examples of suitable epoxy resins are also commercially available from NanYa Plastics under the trademark NPES-903, and from Hexion under the trademarks EPON ^™ 2002 and EPON 2004 ^™ .

The epoxy resin may have 500 or more or 700 or more equivalents. The epoxy resin may also contain up to 1,000 or up to 5,100 equivalents. The epoxy resin may contain 500 to 5,100 or 700 to 1,000 equivalents. As used herein, “equivalent” refers to the weight average molecular weight of a resin divided by the number of functional groups. Thus, the equivalent weight of the epoxy resin is determined by dividing the weight average molecular weight of the epoxy resin by the total number of epoxide groups and any other optional functional groups other than the epoxide. In addition, the weight average molecular weight is determined by gel permeation chromatography based on a linear polystyrene standard of 800 to 900,000 Daltons measured by a Waters 2695 separation module (RI detector) equipped with a Waters 410 differential refractometer. Tetrahydrofuran (THF) was used as the eluent at a flow rate of 1 mL·min ⁻¹ , and two PLgel Mixed-C (300 x 7.5 mm) columns were used for separation.

The binder used to form the coating composition of the present invention also includes two or more epoxy resins. For example, the binder may comprise two or more distinct different epoxy resins, wherein each epoxy resin is independently two or more epoxide functional groups, and, optionally, any other functional groups described above, such as one It contains more than one hydroxyl group. Multiple epoxy resins may have the same or different equivalent weights. For example, the first epoxy resin may have an equivalent weight greater than that of the second epoxy resin.

When two separate epoxy resins are used with the coating composition of the present invention, the second epoxy resin may comprise 500 or more or 700 or more equivalents. The second epoxy resin may also contain 1,000 or less or 5,000 or less equivalents. The second epoxy resin may include an equivalent range of 500 to 5,000 or 700 to 1,000.

In addition, the first epoxy resin may contain 800 or more or 900 or more equivalents. The first epoxy resin may also contain 5,100 or less or 1,100 or less equivalents. The first epoxy resin may include an equivalent range of 800 to 5,100 or 900 to 1,100.

The film-forming resin used to form the binder may comprise a glass transition temperature (Tg) of 35°C or higher or 40°C or higher. Tg is measured using a differential scanning calorimeter (DSC).

The coating composition of the present invention may also comprise at least 15% by weight, at least 30% by weight, at least 50% by weight, at least 60% by weight or at least 75% by weight, based on the total solids weight of the coating composition. have. The coating composition of the present invention may comprise up to 90% by weight or up to 93% by weight of one or more film-forming resins based on the total solids weight of the coating composition. The coating composition of the present invention may also comprise one or more film-forming resins in a range such as 15 to 93% by weight, 50 to 93% by weight, or 60 to 90% by weight, based on the total solids weight of the coating composition.

As mentioned above, any range recited herein includes any subranges contained within such range.

The binder may also include a curing agent that is reactive with the functional groups of the film-forming resin. As used herein, “curing agent” refers to a chemical compound capable of curing or crosslinking a resin material by reacting with a chemical group on the resin. Curing agent Phenolic compounds such as phenolic hydroxyl functional compounds, epoxy compounds, triglycidyl isocyanurate, beta-hydroxy (alkyl) amides, alkylated carbamates, isocyanates, polyacids, anhydrides, organometallic acids -Functional substances, polyamines, polyamides, polyfunctional polyols, aminoplasts, urethdiones such as polyurethdione, boron trifluoride complexes and combinations thereof. The curing agent is not limiting and may include any curing agent that is reactive with one or more functional groups on the film-forming resin.

In some instances, the binder of the present invention may include an epoxy resin having two or more epoxide functional groups and a curing agent reactive with the epoxide groups of the epoxy resin. The curing agent reactive with the epoxy resin may comprise the above-described curing agent reactive with one or more, such as two or more epoxide groups. For example, the curing agent may include a phenolic hydroxyl functional compound. Non-limiting examples of suitable phenolic hydroxyl functional curing agents are commercially available from Hexion under the trademarks EPIKURE ^™ P-201 and P-202. Other examples of suitable curing agents that are reactive with the epoxide groups of the epoxy resin are also disclosed in US Pat. No. 6,521,706 (incorporated herein by reference) at column 7, lines 16-35.

As mentioned, the binder may comprise multiple curing agents that are reactive with the same or different functional groups on the film-forming resin. For example, the binder may be (1) an epoxy resin comprising two or more epoxide groups and one or more hydroxyl functional groups; And (2) the first curing agent is reactive with an epoxide functional group and the second curing agent is reactive with a hydroxyl group. In some examples, the second curing agent can be selected to react with one or more hydroxyl groups on the resin to form urethane linking groups. Such curing agents include, but are not limited to, isocyanates, urethdiones and mixtures thereof. The second curing agent may also be selected to react with a functional group formed from the reaction between the first curing agent and the epoxide functional group.

The coating composition of the present invention may include 3% by weight or more, 10% by weight or more, or 15% by weight or more of one or more curing agents based on the total solid weight of the coating composition. The coating composition of the present invention may comprise 35% by weight or less or 30% by weight or less of one or more curing agents based on the total solids weight of the coating composition. The coating composition of the present invention may also comprise one or more curing agents in a range such as 3 to 35% by weight, 5 to 32% by weight, 10 to 30% by weight or 15 to 30% by weight, based on the total solids weight of the coating composition. have.

In addition, the binder used to form the curable coating composition of the present invention may be solid. As such, the film-forming resin and the curing agent reactive with the film-forming resin constituting the binder may be in a solid form. It is recognized that any of the components that form the binder are initially provided as liquids and/or dispersions and can then be processed into solids using techniques known in the art.

The binder of the present invention may constitute 15% by weight or more, 30% by weight or more, 50% by weight or more, 60% by weight or more, or 75% by weight or more based on the total solid weight of the coating composition. The binder of the present invention may constitute 90% by weight or less, 93% by weight or less, or 96% by weight or less based on the total solid weight of the coating composition. The binder of the present invention may also constitute 15 to 96% by weight, 50 to 96% by weight, 60 to 96% by weight, or 75 to 90% by weight, based on the total solids weight of the coating composition.

The curable coating composition of the present invention also includes vulcanized rubber particles that are non-reactive with the binder. As used herein, "vulcanized rubber particles" refer to particles made of an elastomeric material comprising bonds that crosslink the polymer chains that make up the elastomeric material. For example, the vulcanized rubber particles undergo free radical crosslinking with, for example, peroxides, metal oxides, allyl-based chlorine-containing compounds, phenol-formaldehyde resins, p-benzoquinonedioxime or combinations thereof through sulfur bonds. Can be crosslinked through. Vulcanized rubber particles can also be made from a variety of elastomer materials. Non-limiting examples of suitable rubbers include nitrile rubber, butyl rubber, silicone rubber, ethylene propylene rubber, ethylene propylene diene terpolymer rubber, styrene butadiene rubber, natural rubber, polybutadiene, or combinations thereof.

The vulcanized rubber particles can be obtained from recycled rubber materials. For example, the vulcanized rubber particles used in the curable coating composition of the present invention can be obtained from recycled tires. Thus, the vulcanized rubber particles may contain additional components such as carbon black, and other fillers typically found in the rubber materials of tires.

The vulcanized rubber particles can include a variety of shapes and sizes. For example, the vulcanized rubber particles may comprise an average particle size of 10 μm or more, 15 μm or more, or 25 μm or more. The vulcanized rubber particles may comprise an average particle size of 85 μm or less, 80 μm or less, or 75 μm or less. The vulcanized rubber particles may comprise an average particle size range of 10 to 85 μm, 15 to 80 μm or 25 to 75 μm. As used herein, the "average particle size" Beckman used in-Coulter (Beckman-Coulter) LS ^TM 13 according to the instructions described in the 320 manual Beckman-Coulter LS ^TM 13 320 laser diffraction particle total amount of the particles in the sample determined by size analyzer Refers to the average particle size. In addition, the particle size range of the total amount of particles in the sample used to measure the average particle size may include a range of 5 to 175 μm, 5 to 110 μm or 5 to 90 μm, which is also Beckman-Coulter LS ^TM 13 It is measured by a Beckman-Coulter LS ^TM 13 320 laser diffraction particle size analyzer according to the description described in the 320 manual.

The particle size described above can be obtained by grinding the vulcanized rubber material, for example by grinding the recycled rubber material. Polished vulcanized rubber having the desired particle size can be prepared by any method known to those skilled in the art to achieve this small particle size. In some examples, the vulcanized rubber particles are made to the desired particle size using cryogenic polishing techniques. Non-limiting examples of methods of making vulcanized rubbers having the desired particle size are also described in US Pat. No. 6,521,706 (incorporated herein by reference) at column 6, lines 9-33.

The vulcanized rubber particles may have a glass transition temperature (Tg) of less than -40°C. The vulcanized rubber particles may also have a Tg of less than -45°C or less than -50°C. Tg is measured using the DSC described above. The vulcanized rubber particles may comprise a combination of particles having different Tg. For example, the curable coating composition may independently comprise vulcanized rubber particles comprising any of the Tg described above.

In addition, the vulcanized rubber particles may contain functional groups that do not react with the component forming the binder. Thus, the vulcanized rubber particles do not react with the film-forming resin and the curing agent forming the binder. The functional vulcanized rubber particles may include, but are not limited to, any of the functional groups described above with respect to the film-forming resin, as long as the functional groups do not react with the functional groups found on the film-forming resin and curing agent of the binder. The vulcanized rubber particles also do not react with any other ingredients used with the curable coating composition of the present invention. Since the vulcanized rubber particles do not react with the other components of the curable coating composition, the vulcanized rubber particles may not react with these components forming adducts, core-shell structures or any other covalently bonded arrangement. In some instances, the coating compositions of the present invention do not include elastomeric materials, such as rubber particles, that form bonds with the resin and curing agent.

The vulcanized rubber particles used with the curable coating composition of the present invention may also be solid. As such, the vulcanized rubber particles can be formed from solid elastomeric materials including, but not limited to, solid recycled vulcanized rubber materials. In some examples, the solid vulcanized rubber particles are solid particulate powders. For example, vulcanized rubber particles may include powders made from recycled rubber materials as defined by ASTM D5603-01 (2015), the entire contents of which are incorporated herein by reference.

The coating composition of the present invention may include 1% by weight or more, 5% by weight or more, or 10% by weight or more of vulcanized rubber particles based on the total solid weight of the coating composition. The coating composition of the present invention may also comprise up to 40% by weight, up to 25% by weight or up to 20% by weight of vulcanized rubber particles based on the total solids weight of the coating composition. The coating composition of the present invention may also comprise vulcanized rubber particles in the range of 1 to 40% by weight, 5 to 25% by weight or 10 to 20% by weight, based on the total solids weight of the coating composition.

It has been found that the addition of non-reactive vulcanized rubber particles improves the impact resistance of the coating formed from the curable coating composition of the present invention. The coating also exhibits other desirable properties such as good solubility, appearance, Taber resistance, chip resistance and chemical resistance.

The curable coating composition may also include pigment particles. As used herein, “pigment particles” refer to particles used to impart color to the coating composition. The term "colorant" is used interchangeably with the term "pigment particle". Non-limiting examples of pigment particles include those listed in the Dry Color Manufacturers Association (DCMA). Examples of pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, diazo, aphthol AS, salt type (flake), benzimidazolone, isoindolinone, Isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavantron, pyrantrone, antantrone, dioxazine, Triarylcarbonium, quinophthalone pigments, diketo pyrrolo pyrrole red ("DPPBO red"), carbon black, certain metal oxides, and mixtures thereof.

The coating composition of the present invention may include 0.25 to 50% by weight, 0.5 to 50% by weight, 1 to 40% by weight, or 5 to 30% by weight of one or more pigment particles based on the total solid weight of the coating composition.

Other non-limiting examples of materials that can be used with the coating composition of the present invention include plasticizers, fillers such as, but not limited to, talc, mica, wollastonite, graphite, calcium carbonate, mica-like iron oxide, barium sulfate, clay, antioxidants. , Flow and surface control agents, thixotropic agents, slip aids, catalysts, reaction inhibitors, texturing agents and other conventional auxiliaries.

Particularly useful fillers that may be used with the curable coating composition of the present invention include platey inorganic fillers, needle-shaped inorganic fillers, or combinations thereof. As used herein, “a flake inorganic filler” refers to an inorganic material in flake form. The term “flaky” refers to a structure in which one dimension is substantially smaller than two other dimensions of the structure resulting in a flat type of appearance. Flaky inorganic fillers are generally in the form of laminated lamellas, sheets, platelets, or plates with relatively significant anisometry. The term "acicular inorganic filler" refers to a structure in which one dimension is substantially larger than the other two dimensions of the structure resulting in a needle-like appearance. Flaky inorganic fillers and needle-like inorganic fillers can also improve the impact performance of the resulting coating.

Flaky and acicular inorganic fillers can have a high aspect ratio. Suitable high aspect ratio flaky and acicular inorganic fillers include, but are not limited to, vermiculite, mica, talc, wollastonite, chlorite, metal flakes, flaky clay and flaky silica. Such fillers typically, but are not limited to, have a diameter of 1 to 100 μm, 2 to 25 μm or 2 to 50 μm. The aspect ratio of these fillers may be at least 5:1, such as at least 10:1 or 20:1. For example, mica flakes may have an aspect ratio of 20:1, talc may have an aspect ratio of 10:1 to 20:1, and vermiculite may have an aspect ratio of 200:1 to 10,000:1. have.

In some instances, the curable coating composition of the present invention is substantially free of, essentially free of, or completely free of fiberglass. The term “fiberglass” as used herein refers to a continuous strand of glass fibers that can be extruded into fine filaments. In addition, the term "substantially free of fiberglass" means that the curable coating composition contains less than 1,000 ppm of fiberglass based on the total weight of the composition, and "essentially free of fiberglass" means curable It is meant that the coating composition contains less than 100 ppm of fiberglass based on the total weight of the composition, and "no fiberglass" means that the curable coating composition is less than 20 ppb of fiberglass based on the total weight of the composition. Means containing. In some instances, the absence of fiberglass in the curable coating composition helps to provide a cured coating having a better visual appearance and/or impact resistance.

The binders described above, the vulcanized rubber particles and optional additional ingredients can be combined to form a powder coating composition. "Powder coating composition" refers to a coating composition contained in a solid particulate form as opposed to a liquid form. Thus, the components described above can be combined to form a curable solid particulate powder coating composition. For example, the binder, vulcanized rubber particles and optional additional ingredients can be combined to form a free flowing curable solid particulate powder coating composition. With respect to the curable solid particulate powder coating composition of the present invention, the term "free flowing" as used herein refers to a curable solid particulate powder composition with minimal aggregation or aggregation between individual particles.

The curable solid particulate powder coating composition can be prepared by mixing a binder, vulcanized rubber particles non-reactive with the binder, and optional additional ingredients in solid form. It may be appreciated that some optional additives are provided as liquids or dispersions and may be formed into solid materials. The solid ingredients are mixed to form a homogeneous mixture. The solid ingredients can be mixed using art-recognized techniques and equipment, such as Prism high speed mixers. The homogeneous mixture is then melted and further mixed. The mixture may be melted with a twin screw compressor or similar apparatus known in the art. During the melting process, the temperature can be selected to melt mix the solid homogeneous mixture without curing the mixture. In some examples, the homogeneous mixture comprises a first zone set to a temperature of 40 to 60°C, such as 45 to 55°C, and a second, third and fourth zone set to a temperature of 70 to 110°C, such as 75 to 100°C. It can be melt-mixed in a twin screw extruder having. After melt mixing, the mixture is cooled and resolidified. The resolidified mixture is then polished, for example in a grinding process, to form a solid particulate curable powder coating composition. The resolidified mixture can be ground to any desired particle size. For example, in electrostatic coating applications, any re-solidified mixture, Beckman-Coulter LS ^TM 13 according to the instructions described in the 320 manual Beckman-Coulter LS ^TM 13 320 laser diffraction particle size by the analyzer measured, more than 10 μm or It can be polished to an average particle size of 20 μm or more and 100 μm or less. In addition, the particle size range of the total amount of particles in the sample used to measure the average particle size may include a range of 1 to 200 μm, 5 to 180 μm or 10 to 150 μm, which is also Beckman-Coulter LS ^TM 13 It is measured by a Beckman-Coulter LS ^TM 13 320 laser diffraction particle size analyzer according to the description described in the 320 manual.

The curable coating composition of the present invention can be applied to a variety of substrates known in the coating industry. For example, the coating composition of the present invention is a substrate for automobiles, industrial substrates, aircraft and aircraft parts, packaging materials, wood flooring and furniture, clothing, electronic devices (including housings and circuit boards), glass and windows, sports equipment (golf balls). Included), etc. These substrates can be metal or non-metal, for example. Metal substrates include, but are not limited to, tin, steel (especially electro-galvanized steel, cold rolled steel, hot-dip galvanized steel), aluminum, aluminum alloy, zinc-aluminum alloy, zinc-aluminum alloy coated steel , And aluminum plated steel. Non-metallic substrates are polymers, plastics, polyesters, polyolefins, polyamides (nylon), cellulose, polystyrene, polyacrylic, poly(ethylene naphthalate), polypropylene, polyethylene, EVOH, polylactic acid, and other "green" polymers. Substrate, poly(ethylene terephthalate) (PET), polycarbonate, polycarbonate/acrylonitrile-butadiene styrene copolymer blend (PC/ABS), wood, veneer, wood composite, particle board, medium density fiber board, Includes cement, stone, glass, paper, cardboard, textiles, leather (both synthetic and natural), and the like.

The curable coating composition of the present invention is particularly advantageous when applied directly to a metal substrate or a pretreated metal substrate. For example, the curable coating composition of the present invention is particularly advantageous when applied to metal springs or coils such as cold rolled steel coils, galvanized steel coils and aluminum coils.

The curable coating composition of the present invention may be applied by any standard method in the art, such as spraying, electrostatic spraying, or the like. The coating formed from the coating composition of the present invention may be applied with a dry film thickness of 2 to 1,800 μm, 50 to 1,000 μm, or 300 to 800 μm.

The coating composition may be applied to a substrate to form a monocoat. As used herein, “monocoat” refers to a single layer coating system without an additional coating layer. Thus, the coating composition can be applied directly to the substrate and cured to form a single layer coating, i.e. a monocoat. When the curable coating composition is applied to a substrate to form a monocoat, the coating composition may include additional ingredients that provide other desirable properties. For example, the curable coating composition may also include an inorganic component that acts as a corrosion inhibitor. As used herein, “corrosion inhibitor” refers to a component such as a material, substance, compound or composite that reduces the rate or severity of corrosion of a surface on a metal or metal alloy substrate. The inorganic component acting as a corrosion inhibitor may include, but is not limited to, an alkali metal component, an alkaline earth metal component, a transition metal component, or a combination thereof.

The term "alkali metal" refers to an element of group 1 of the periodic table of chemical elements (International Union of Pure and Applied Chemistry (IUPAC)), for example cesium (Cs), francium (Fr) , Lithium (Li), potassium (K), rubidium (Rb) and sodium (Na). The term "alkaline earth metal" refers to an element of Group 2 of the periodic table of chemical elements (IUPAC) and includes, for example, barium (Ba), beryllium (Be), calcium (Ca), magnesium (Mg) and strontium (Sr). . The term "transition metal" refers to an element of Group 3-12 of the periodic table of chemical elements (IUPAC), and includes, for example, titanium (Ti), chromium (Cr) and zinc (Zn), among others.

Specific non-limiting examples of inorganic components that act as corrosion inhibitors are magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium phosphate, magnesium silicate, zinc oxide, zinc hydroxide, zinc carbonate, zinc phosphate, zinc silicate, zinc dust. And combinations thereof.

Alternatively, the curable coating composition can be applied over a first coating layer deposited on a substrate to form a multi-layer coating system. For example, the coating composition can be applied to the substrate as a primer layer, and the curable coating composition described above can be applied on the primer layer as a topcoat. As used herein, “primer” refers to a coating composition in which an undercoating can be deposited on a substrate to prepare a surface for application of a protective or decorative coating system. Basecoats can also be used with multi-layer coating systems. “Basecoat” refers to a coating composition in which a coating is deposited on a primer and/or directly on a substrate, which optionally changes color and/or provides other visual changes and is overcoated with a protective and decorative topcoat ( It contains ingredients (eg, pigments) that can be overcoated.

In some examples, a first coating layer, such as a primer layer, can be applied directly on the substrate to protect the substrate from corrosion, and the curable coating composition described above can be applied on the first coating layer to provide at least impact resistance. connect. As such, the first coating layer is a film-forming resin, such as, but not limited to, any film-forming resin described above, optionally, a curing agent, such as, but not limited to, any curing agent described above, a corrosion inhibitor. Functional inorganic components, and, optionally, other additives described above. Inorganic components that act as corrosion inhibitors and can be used with the first coating layer may include, but are not limited to, any of the inorganic corrosion inhibitory components described above.

It is recognized that a curable coating composition comprising solid vulcanized rubber particles can be used as the first coating layer in a multi-layer coating system. When used as the first layer, the curable coating composition may contain additional components such as the inorganic corrosion inhibiting components described above. The second coating layer applied on the first coating layer may comprise a coating made from a curable coating composition comprising vulcanized rubber particles. The second coating layer can also be made from different coating compositions as known in the art.

It has been found that the curable coating composition of the present invention, when applied to a metal substrate and cured to form a coating, provides good impact resistance, flexibility and a visible appearance. Curable coating compositions have also been found to provide good impact resistance, flexibility and visible appearance when used as a topcoat in a multi-layer coating system.

The following examples are presented to demonstrate the general principles of the invention. The invention should not be considered limited to the specific examples presented. All parts and percentages in the examples are by weight unless otherwise indicated. In addition, with respect to the tables listed in Haga Examples, the abbreviation "Comparative Example" means "Comparative Example".

Examples 1 to 7

*Preparation of curable coating composition

Seven curable coating compositions were prepared from the ingredients listed in Table 1.

[Table 1]

¹ An epoxy resin based on the diglycidyl ether of bisphenol A having an equivalent weight of about 700 to 750 (commercially available from Nanya Plastics).

² An epoxy resin based on the diglycidyl ether of bisphenol A having an equivalent weight of about 875 to 975 (formed from bisphenol A and epichlorohydrin) (commercially available from Hexion).

³ Solid diglycidyl ether of bisphenol A and adduct of liquid rubber (commercially available from Emerald Performance Materials).

⁴ Acrylic/silica flow and leveling control agent (commercially available from Estron Chemical).

⁵ Benzoin (commercially available from Mitsubishi Chemical Corp.).

⁶ Accelerator for high temperature curing of epoxy resin formulations (commercially available from ALZ Chem).

⁷ Carbon black (commercially available from Cabot).

⁸ Phenolic hydroxyl terminated solid flake hardener containing accelerator (commercially available from Hexion).

^{9 According} to ASTM D5603-01 (2015) with an average particle size range of 10 to 85 μm measured by a Beckman-Coulter LS ^TM 13 320 laser diffraction particle size analyzer according to the description described in the Beckman-Coulter LS ^TM 13 320 manual. Free flowing black powder made from recycled vulcanized rubber material as defined by.

¹⁰ Alicyclic polyurethane (commercially available from Bayer) without blocking agent.

Each component listed in Table 1 for Examples 1 to 7 was weighed in a container and mixed in a prism high speed mixer at 3,500 RPM for 30 seconds to obtain a dry homogeneous mixture. The mixture was then melt mixed in a Werner Pfleiderer 19 mm twin screw extruder using cohesive screw centrifugation and a speed of 500 RPM. The first zone was set to 50°C, and the second, third and fourth zones were set to 80°C. The feed rate was such that 50-60% of torque was observed on the equipment. The mixture was dropped onto a set of chill rolls to cool, and the mixture was resolidified into solid chips. The chips were pulverized in a Mikro ACM ^® -1 Air Classifying Mill to obtain an average particle size of 10 to 100 μm. The resulting coating composition for each of Examples 1-7 was a free flowing solid particulate powder coating composition.

Example 8

Application of solid particulate powder coating

A first powder coating composition comprising an epoxy resin, a curing agent reactive with the epoxy resin, and a zinc component was applied onto various high tensile strength steel coil springs. The first powder coating composition was applied to a thickness of 25 to 100 μm onto the preheated substrate at 375° F. for about 25 to 35 minutes to form a first coating layer. Subsequently, each of the solid particulate powder coating compositions of Examples 1 to 7 was electrostatically sprayed onto the first coating layer, with the first coating layer still hot. The solid particulate powder coating compositions of Examples 1 to 7 were applied to a thickness of 350 to 1,000 μm, and baked at 375° F. for about 35 minutes.

Example 9

Evaluation of impact resistance

Each of the multi-layer coatings prepared from the compositions of Examples 1 to 7 was evaluated for the final dry film thickness and impact resistance of the primer + topcoat. The resulting film was measured with a dry film gauge model number 415 from Elcometer. The impact resistance of each coating system was measured according to ISO 4532 at -40°C. The "Pistol" test instrument was set to a load of 90 N. The coil spring was left in the freezer at -40°C for 24 hours, then removed, and a shock was applied to the coil spring surface at a 90° angle within 30 seconds of being removed from the freezer.

Each coating was tested several times for impact resistance using the test described above. Coatings that exhibited physical damage, such as chipping, were recorded as failures. The% failure was then determined based on the total number of tests administered for each type of coating. The results are presented in Table 2.

[Table 2]

As shown in Table 2, the coatings prepared from the coating compositions of Examples 6 and 7 (including the topcoat according to the present invention) showed the best impact resistance with the lowest failure rate. In addition, both coatings prepared from the coating compositions of Comparative Example 4 (which included the solid diglycidyl ether of bisphenol A and the adduct of liquid rubber) and Comparative Example 5 (which included crushed fiberglass) were 100% failure.

The invention also includes the following aspects.

Aspect 1: (a) (i) a film-forming resin comprising two or more functional groups; And (ii) a binder comprising a curing agent reactive with the functional group of (i); And (b) a curable coating composition comprising solid vulcanized rubber particles non-reactive with the binder, wherein the curable coating composition is a solid particulate powder coating composition.

Aspect 2: The curable coating composition according to the first aspect, wherein the film-forming resin has a glass transition temperature (Tg) of 35° C. or higher, such as 40° C. or higher.

Aspect 3: The curable coating composition of the first aspect or the second aspect, wherein the film-forming resin comprises an epoxy resin having at least two epoxide groups and the curing agent is reactive with the epoxide groups.

Aspect 4: The curable coating composition of aspect 3, wherein the epoxy resin further comprises one or more hydroxyl groups.

Aspect 5: The curable coating composition of aspect 4, further comprising a second curing agent reactive with hydroxyl groups.

Aspect 6: The curable coating composition of any one of aspects 3 to 5, wherein the epoxy resin has an equivalent weight of 500 to 5,100.

Aspect 7: of the first aspect or the second aspect, wherein the curable coating composition each independently comprises at least a first epoxy resin and a second epoxy resin comprising at least two epoxide groups, and the curing agent is reactive with the epoxide groups , The first epoxy resin has an equivalent weight greater than that of the second epoxy resin, curable coating composition.

Aspect 8: The curable coating composition of aspect 5 or 7 wherein the first and/or second epoxy resin further comprises one or more hydroxyl groups.

Aspect 9: The curable according to aspect 7 or 8, wherein the first epoxy resin has an equivalent weight of 800 to 5,100, such as 900 to 1,100, and the second epoxy resin has an equivalent weight of 500 to 5,000, such as 700 to 1,000. Coating composition.

Aspect 10: The curable according to any one of aspects 1 to 9, wherein the solid vulcanized rubber particles have an average particle size of 85 μm or less, such as 10 to 85 μm, 15 to 80 μm or 25 to 75 μm. Coating composition.

Aspect 11: according to any one of the first to tenth aspects, wherein the solid vulcanized rubber particles are not more than 40% by weight of the coating composition, such as 1 to 40% by weight, preferably based on the total solids weight of the coating composition. Comprising 5 to 25% by weight, more preferably 10 to 20% by weight, curable coating composition.

Aspect 12: The curable coating composition of any one of aspects 1 to 11, wherein the vulcanized rubber particles have a glass transition temperature (Tg) of less than -40°C, such as less than -45°C or less than -50°C. .

Aspect 13: The curable coating composition of any one of aspects 1-12, further comprising pigment particles.

Aspect 14: According to any one of the first to thirteenth aspects, comprising less than 1,000 ppm fiberglass, preferably less than 100 ppm fiberglass, more preferably fiberglass, based on the total weight of the composition. Does not contain at all, curable coating composition.

Aspect 15: The curable coating composition of any one of aspects 1 to 14, further comprising a flake inorganic filler, an acicular inorganic filler, or a combination thereof.

Aspect 16: according to any one of the first to fifteenth aspects, comprising less than 1,000 ppm of thermoplastic resin, preferably less than 100 ppm of thermoplastic resin, more preferably thermoplastic resin, based on the total weight of the composition Curable coating composition that does not contain at all.

Aspect 17: The curable coating composition of any one of aspects 1 to 16, further comprising an inorganic corrosion inhibiting component comprising a transition metal component, an alkali metal component, an alkaline earth metal component, or a combination thereof.

Aspect 18: According to any one of the first to seventeenth aspects, based on the total solids weight of the coating composition, 15 to 93% by weight, 30 to 90% by weight, 40 to 85% by weight, 50 to 85% by weight or A curable coating composition comprising 60 to 80% by weight of one or more film-forming resins.

Aspect 19: According to any one of the first to eighteenth aspects, based on the total solids weight of the coating composition of 3 to 35% by weight, 5 to 32% by weight, 10 to 30% by weight or 15 to 25% by weight A curable coating composition comprising one or more curing agents.

Aspect 20: The curable coating composition of any one of aspects 1 to 19, consisting of particles having an average particle size of 20 to 100 μm.

Aspect 21: (a) mixing a combination of solid components to i) a film-forming resin comprising two or more functional groups; ii) a curing agent reactive with the functional group of i); And iii) preparing a mixture comprising the film-forming resin of i) and the vulcanized rubber particles non-reactive with the curing agent of ii); (b) melting the mixture prepared in (a) and further mixing; (c) cooling the molten mixture; And (d) polishing a mixture of solid components to prepare a solid particulate curable powder coating composition. 2. A method of preparing a curable coating composition according to any one of the first to twentieth aspects.

Aspect 22: (a) a first coating layer; And (b) a second coating layer deposited on the first coating layer, wherein the first coating layer and/or the second coating layer is according to any one of the first to twentieth aspects. Manufactured from, a multi-layer coating system.

Aspect 23: The multi-layer coating system of aspect 22, wherein the first coating layer comprises an inorganic corrosion inhibiting component comprising a transition metal component, an alkali metal component, an alkaline earth metal component, or a combination thereof.

While certain aspects of the invention have been described above for purposes of explanation, it will be apparent to those skilled in the art that numerous modifications of the details of the invention can be made without departing from the invention defined in the appended claims.

Claims (21)

A substrate at least partially coated with a curable coating composition, wherein the curable coating composition
(a) (i) a film-forming resin comprising two or more functional groups; And (ii) a binder comprising a curing agent reactive with the functional group of (i); And
(b) solid vulcanized rubber particles non-reactive with the binder
Including,
The curable coating composition is a solid particulate powder coating composition,
The solid vulcanized rubber particles are not a component of the core-shell structure, the substrate. The method of claim 1,
A substrate, wherein the substrate comprises a metal substrate. The method of claim 1,
A substrate, wherein the substrate comprises a spring and/or coil. The method of claim 3,
A substrate, wherein the spring and/or coil comprises cold rolled steel, galvanized steel, aluminum, or combinations thereof. The method of claim 1,
A substrate, wherein the substrate comprises a non-planar substrate. The method of claim 1,
The substrate, wherein the solid vulcanized rubber particles have an average particle size of 10 to 85 μm. The method of claim 1,
A substrate at least partially coated with a multi-layer coating system,
The multi-layer coating system comprises a first coating layer; And a second coating layer deposited on the first coating layer,
The substrate, wherein the second coating layer is prepared from the curable coating composition. The method of claim 7,
The substrate, wherein the first coating layer is made from a composition comprising a film-forming resin and a corrosion inhibitor. The method of claim 8,
The substrate, wherein the corrosion inhibitor comprises a transition metal component, an alkali metal component, an alkaline earth metal component, or a combination thereof. The method of claim 1,
A substrate, wherein the film-forming resin comprises an epoxy resin having at least two epoxide groups, and the curing agent is reactive with the epoxide groups. The method of claim 10,
The substrate, wherein the epoxy resin further comprises one or more hydroxyl groups. The method of claim 1,
The substrate, wherein the solid vulcanized rubber particles have a glass transition temperature (Tg) of less than -40°C. The method of claim 1,
The substrate, wherein the solid vulcanized rubber particles constitute up to 40% by weight of the curable coating composition based on the total solids weight of the curable coating composition. The method of claim 1,
A substrate in which the curable coating composition does not contain any fiberglass. A spring at least partially coated with a curable coating composition, wherein the curable coating composition
(a) (i) a film-forming resin comprising two or more functional groups; And (ii) a binder comprising a curing agent reactive with the functional group of (i); And
(b) solid vulcanized rubber particles non-reactive with the binder
Including,
The curable coating composition is a solid particulate powder coating composition,
The solid vulcanized rubber particles are not a component of the core-shell structure, spring. As a method of improving the impact resistance of the substrate, comprising applying a curable coating composition to the substrate,
The curable coating composition
(a) (i) a film-forming resin comprising two or more functional groups; And (ii) a binder comprising a curing agent reactive with the functional group of (i); And
(b) solid vulcanized rubber particles non-reactive with the binder
Including,
The curable coating composition is a solid particulate powder coating composition,
The method, wherein the solid vulcanized rubber particles are not a component of a core-shell structure. The method of claim 16,
The method, wherein the substrate comprises a metal substrate. The method of claim 16,
The method, wherein the substrate comprises a spring and/or a coil. The method of claim 18,
The method, wherein the spring and/or coil comprises cold rolled steel, galvanized steel, aluminum, or combinations thereof. The method of claim 16,
The method, wherein the substrate comprises a non-planar substrate. A coil at least partially coated with a curable coating composition, wherein the curable coating composition
(a) (i) a film-forming resin comprising two or more functional groups; And (ii) a binder comprising a curing agent reactive with the functional group of (i); And
(b) solid vulcanized rubber particles non-reactive with the binder
Including,
The solid vulcanized rubber particles are not a component of a core-shell structure,
The coil, wherein the curable coating composition is a solid particulate powder coating composition.